In the military circumstances of today, there is a continuing need for camouflage which has several rather specific requirements, depending upon the use to which it will be put. The older and more obvious requirements are that the camouflage must be capable of presenting a visual appearance similar to the surroundings, i.e., it must look like snow when it is designed for use in an arctic environment, or it must look like soil or vegetation or some combination thereof, when it is to be used to conceal an object in a woodland environment. The camouflage fabric must also be flexible so that it can be draped over an object, with or without a support framework, and it must be light enough in weight so that it can be easily handled by one or a few individuals and placed in the desired location.
As the art of making camouflage has improved, so have the techniques of detecting deployed camouflage. Thus, it is now desirable to provide camouflage which has infrared reflectance and thermal emission characteristics similar to the environment, in addition to the visual characteristics. Also, for many applications, the camouflage fabric must present a reflected radar signal similar to the environment to avoid detection by radar. If the camouflage fabric has all of these characteristics, it is possible to avoid detection by infrared, thermal imaging, optical observation devices, and radar.
In the prior art efforts to provide camouflage meeting these, and other requirements, it has become customary to provide a multi-layered camouflage netting system, typically a base layer and an outer layer. The outer layer, or garnish, is typically coated or printed with at least one pigmented coating layer, the coating layer or layers being designed to provide the desired optical characteristics (visual, infrared and thermal). The garnish layer may be incised or cut, stretched and then attached to the base layer to produce a three-dimensional leaf structure as described in U.S. Pat. Nos. 4,323,605 and 3,069,796.
In order to provide adequate radar concealment, the total transmission of the net system to radar waves must be lower than 50%. Traditionally, a radar absorbing material such as carbon or graphite is coated onto one or both layers of fabric. In order to achieve the necessary system conductivity to be effective at blocking transmission of radar waves, both layers of fabric often must be coated with carbon-containing coating. While camouflage material of both radar defeating and radar transparent types has been successfully produced with this combination of materials, certain shortcomings have become apparent. To have the required amount of conductivity using carbon or graphite, thicker coatings must often be applied adding considerably to the total weight of the camouflage material. Additionally, highly loaded coatings containing carbon black have been shown to have limited durability to abrasion and reduced strength of the material.
Concealment properties of radar camouflage may be improved by providing radar absorbing and reflecting material that has a vertical component. Rush in U.S. Pat. No. 4,323,605, provided a three-dimension garnish layer with a percentage of the garnish layer having a radar active coating oriented in the vertical plane demonstrating an improved radar signature degradation over single plane radar active layers.
There remains a need to provide a camouflage netting system with radar absorbing material on the garnish layer, where the garnish layer is cut to reveal voids and provide a three-dimensional radar active surface that has improved radar camouflage and visual camouflage characteristics as well as being light weight and durable.